Knife grinder



May 11, 1943.

G, P. DoRRxs 2,318,764

KNIFE GRINDER Filed April 19, 1941 llllillL:

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Patented May 11, 1943 KNIFE GRINDER George P. Dorris, St. Louis, Mo., assignor, by direct and trustee mesne assignments, to said Dorris,

Application April 19, 1941, Serial No. 389,308

1 Claim.

This invention pertains to grinding apparatus, and more particularly to knife grinders for` use 'in butcher shops Iand similar establishments where knives must be frequently sharpened.

,One of the objects of this invention is to provide a grinder for knives so `arranged that a knife vmay be applied to the grinder in a simple manner, and in which guiding and locating devices are arranged to insure the grinding of a proper edge without requiring any high degree of skill on the part of the operator.

Another object is to provide such a grinder, having arrangements for positively preventing a knife blade from becoming jammed in the device.

Another object is to provide such a device arranged for simple adjustment to vary the angle of the ground edge.

Another object is to provide such ian apparatus of improved construction which may be accurately adjusted .to take up wear and which may also be provided with suitable means to carry off the grinding dust.

Further objects will appear from the following description, taken in connection with the accompanying drawing, in which:

Figure 1 is a plan view of an apparatus embodying this invention;

Figure 2 is a view in end elevation of the same;

Figure 3 is a view in side elevation;

Figure 4 is a vertical ysection on line 4-4 of Figure 1;

Figure 5 is a vertical section on line 5-5 of Figure 1; and

Figure 6 is a horizontal section taken on line I(i--l of Figure 5.

Referring to the accompanying drawing, the embodiment of the invention selected for illustration therein is arranged to be mounted upon a motor I having a vertical shaft 2. A supporting base 3 for the grinder is arranged for attachment to the iframe o-f the motor I as by means of screws 4 or other suitable fastenings. The base 3 may have the horizontal contour shown in Figure 6, |and has 1an internal bore providing therewithin an upper chamber 5 Aand a lower chamber 6. These chambers lare separated by a baille plate 'I resting on a shoulder 8 of the base and having a central opening 9.

The upper part of the base 3 is provided with an internal thread IIJ, into which is threaded a barrel II. This barrel may be provided with a series of recesses I2, adapted to receive a suitable tool for adjusting the barrel Il by rotating the same in the threads IG in order to raise and lower it. The barrel II is further provided with an annular shoulder I3, upon which is mounted a working table I4.

Mounted on the shaft 2 and secured for rotation therewith isa grinding element in the form of a cup-shaped wheel I5 of suitable abrasive-material. This wheel ts within the bore of the barrel I I, allowing a slight air space i6 therebetween. Mounted on the table i4, and so as to extend over 1a portion of the grinding wheel I5 and the table lli, is a bridge II. This bridge is hollowed out underneath so as to clear the grinding wheel, but rests at its edges upon the table I4. The entire assembly may beheld in place by a pair of studs I8 threaded into the base 3 at their lower ends. At their upper endssuitable thurnb nuts I9 may be threaded on the studs I8 so las to bear upon the bridge il and clamp the entire assembly together.

The bridge I'I in the embodiment illustrated carries a blade stop 29 extending approximately diametri-cally across the grinding wheel and having a downwardly extending middle portion 2| extending into the hollow of the cup-shaped grinding wheel. This stop Iis preferably constructed of hardened steel so as to withstand wear.

Pivoted at 22 lon the table I4 is a blade-engage- -able guide plate 23. This plate may be provided with downwardly extending side wings 24 which may extend along the sides of the table I4, and one of which may be provided with a suitable scale, indicated [at 25, to show the adjusted angular position of this plate. A suitable adjusting screw 26 threaded into the table I4 may be provided to adjust the angle of the plate 23. The inner edge of the plate 23 may be provided with notches 2'I so that it may clear the working race of the grinding wheel, leaving between said notches a tongue which may extend down into the hollow of the grinding wheel, as shown in Figure 5. I

Mounted on the shaft -2 for rotation therewith within the lower chamber '6 of the base is a fan 2-8. This fan is arranged below the baille plate 1 so as to draw air downwardly -through the air space I8 around the grinding wheel in order to carry away the cuttings which are discharged through one or more exhaust ports 29 in the lower part of the base 3.

In the use of this device the motor I, having been set in operation, rotates the grinding wheel and the fan 28. The operator, having adjusted the plate 23 to the desired angle as indicated on the scale 23, places the knife blade to be ground against the plate 23 in the positions indicated at 30 in dotted lines. The flat face of the blade is laid down against the plate 23, and the edge to be ground is placed against the blade stop 20. This locates the blade so as to position it at a proper angle with respect to the upper grinding face of the wheel I5. By holding it against the stop 2U and moving it lengthwise while maintaining the ground edge in contact with said stop, the knife is guided so as to maintain it always in properrelation to the grinding wheel. Accordingly, it is necessary only to stroke the knife blade back and forth a few times across the? grinding wheel, While maintaining it thus inengagement with the plate 23 and the stop 20 in order to grind an even and uniform angle all along the blade. The blade is easily 'turned at the curved tip so as to maintain this relation with the grindingwheel. Theblademaythen beturned over Y and the opposite side ground in the same mannel'. Meanwhile, the fan 28 creates a suction in the air space IB, which draws the dust produced by the grinding operation downwardly through this space and into the chamber 5. At this point the baffle 'I deects the air radially inwardly so that it passes through the opening 9 into the central portion of the chamber 6 and in proper relation to the fan 28, to be taken up thereby and forced out at the ports 29. If desired, any suitable duct system may be connected to the ports 2'9 so as to carry oi and dispose of the dust in any desired manner.

It will be seen that this invention accomplishes its objects in providing a grinding device whereby butcher knives and the like may be ground accurately Without requiring any particular skill on the part of the operator.

The plate 23 xes i the angle to which the blade is ground. The stop 20 prevents the blade from shifting too far downwardly along the plate 23, and therefore insures the formation of a smooth and uniformly ground edge. As this stop plate extends into the hollow of the grinding wheel, it will be seen that it is impossible for the blade to become jammed between the wheel and this stop. Ac cordingly, the blade is always freely movable on the plate 23, and the grinding operation may be carried out with ease.

It is obvious that various changes may be made in the details of construction within the scope of the appended claim without departing from the spirit of this invention. It is understood, therefore, that the invention is not limited to the specific details shown and described.

The invention having thus been described, what is claimed is:

A knife grinder, comprising, motor means having an upright shaft, a cup-shaped grinding wheel on said shaft having a flat grinding rim moving in a substantially horizontal plane, a supporting table mounted for vertical adjustment relative to said plane, a blade-engageable guide plate pivoted on said table on an axis transverse to and adjacent the axis of said wheel, means for angularly adjusting said plate on said pivot axis, and a blade-edge guide supported above said wheel and extending downwardly into the hollow thereof and having a blade-engageable face positioned on the opposite side of said wheel axis from said guide plate so as to permit the blade to engage said grinding. rim adjacent a point thereof on a diameter parallel to said face.

GEORGE P. DORRIS. 

